Manufacture of borax and boric acid.



E..L. PLBMING. IMANUFAGTUBE 0F BOEAX AND BORIC ACID.

APPLICATION :FILED JULY l0, 1911.

LOQQ,

lPatented ManZlQI.

Z SHEETS-SHEBT 1.

LLM Ll Plv.

E. L; FLEMING.

MANUFAGTUBE DF BORAEAND BORIG ACID. Arwmfmf; umn, JULY 1o, 1911.

'fgng Patented Mar. 17,19%.

2 SHEETS-SEBBT 2.

EREST LALREMON FLEMING, 0F CHESTER, ENGLAND.

MANUFCTURE 0F BORAX AND BORIC ACD.

Losetas.

Specification of Letters Patent.

Application led July 10, 1911.

Patented raar. iv, tere. Serial No. 637,762.

To all whom it may concern Be it known that I, `ERNEST LAnEMoNT FLEAUNG, a subject of the King ot Great Britain, and a resident of Chester, England, have invented certain new and use'tul lnk provenients in the Manufacture ot Borax and Boric Acid, of which the following is a specification.

Borax is at present largely prepared by. boiling, either singly or conjointly, thel various naturally occurring borates of lime or double borates of lime and soda together with sesquicarbonate of soda, or an equivabonates, in the .presence of water. After removal of the precipitated calcium carbonate the liquor containing the boraX is setaside or otherwise treated in order to 0btain the latter in crystalline form; the borax so obtained being further refined by re-solution in, and recrystallization from, water. y One of the known methods of preparing boric acid is .by agitat-ing and boilingthe finely ground naturally occurring borates above referred to, together with diluted sulfuric acid. The mass so obtained is allowed to settle and the clear liquor containing the boric acid after being separated from the de posited calcium sulfate is run into suitable vessels in which the acid crystallizes out and is recovered. At the present time also brine is electrolytically treated for the puri pose. of obtaining caustic soda and chlorin gas; the latter being largely used for saturating calcium hydrate in order to produce bleaching powder.

According to the present invention the methods of preparing borax'as above referred to and that relating to the electrolysis of brine are combined and elaborated so that by means of a particular arrangement of plant, hereinafter described, borax, boric acid, and Chlor-ate of soda may be produced.

The. process is described with reference to the accompanying drawings which are merely diagrammatic and for the purposeof assisting the description. In said drawings Figure l represents a side elevation (diagrammatic.) of an apparatus suitable for usein carrying out my process, and Fig. 2, represents an end elevation of the same apparatus, the electrolytic cells, the carbouators, and the scrubbers being omitted from this ligure in order to avoid confusion.

In carrying out the invention, crude borate of lime, or borate of lime and soda, or a mixture .ofboth these substances, is intimately mixed with brine in a suitable vessel by means of an agitator. 'The slurry so obtained is then either pumped into settling tanks A and allowed to deposit its sediment, the clear brine being drawn olil to vats B by pipes b as requiredg-or it may alternatively be filtered; the object in either case being to recover the brine in a claried state and to obtain a' thoroughly moistened mass of borate material. The borate is passed or conveyed to a decomposing vessel C technically known as a saturator where it is boiled up and thoroughly agitated With the carbonated liquor de-v rived from the carbonators D to be presently described. The clear brine from theV set- B, or as otherwise obtained, and preferably responds to about 83%, is passed on to and decomposed in a series of suitable electrolytic cells E bywhich means a solution of caustic soda is obtained at the cathode 'and an equivalent amount of chlorin liberated at the anode. Owing to the solubility of the chlorin in water the anode liquor always contains more or less chlorin in solution. This liquor is therefore utilized for a purpose to be described subsequently and is hereinafter referred to as the anode liquor. The caustic lsoda solution obtained at the cathode is transferred by pipes CZ to the carbonators and there treated for the purpose of carbonating it, withrcarbon di-oXid gas, which may be obtained in any convenient manner. The exhaust gases from the internal combustion engines F which may form part of the plant may be advantageously utilized for this purpose, in which ease the gases are passed through scrubbers `Gr from which, after being'niixed with a further supply if desired of carbon di-oXid gas obtained in a manner to be hereinafter described from the calcium carbonate residues separated from the borax liquor, they are sent on directly to the carbonalors D by pipes g. The carbonating of the caustic soda liquor is carried on until the composition of the carbonate of soda therein produced approximately corresponds to that or' the sesquiearl'ionate when it is transferred by the puin]J H andpipe 7i to the rats J and thence by ,pipes j to the decomposing vessel l n containing about 42 ozs. of salt' `(sodium chlorid) to the gallon, which coror saturator C previously referred to. It is here thoroughly mixed, agitated, and boiled up with the moist borate of lime obtained from vessel A as above described, the proportions ot borate and carbonated liquor being regulated according to the previously ascertained composition of each, a lter the manner above described for borax umnutacture.

When the react-ion between the carbonated soda liquor and the borate material is complete, the whole ot' the liquor from the decomposing pan C, which holds the borax 'formed in solution and the calcium carbonate which is simultaneously produced in suspension, is passed through a centrifugal K, by which means the bulk of the calcium carbonate is removed and a liquor obtained which is further clarified by passing it through a filter press L.

The calcium carbonate obtained trom this and the preceding treatment in the centrifugal, is taken by means ot a conveyer or in other suitable manner to the exhaust gas scrubbers Gr. where it is treated as hereafter described for the purpose of recovering some of its carbon.diox.i.d gas. The hot liquor from the filter press L which contains the borax is then passed over a refrigerator M, as a result. ot which treatment part of the borax crystallizes out and is collected, leaving a remainder in solution, which passes by pipe m. Any adhering liquid is removed from the crystallized borax thus obtained and its drying completed by treating it in a hydro extractor N, the liquor from which passes by pipe n and after being mixed with the original mother-liquor from Vthe borax crystals is then concentrated in suitable pans O till its density reaches G0 degrees Twaddell. When of this specific gravity the hot liquor is passedinto a chlorinating vessel P where, its temperature being maintained by steam coils or other heat, it is subjected to the action of a currentof chlorin gas which as previously described has been produced by the electrolytic decomposition of the original brine and conveyed to the chlorinator by pipes e. Decomposition of the borax remainlng in solution in the hot liquor takes place-under these conditions; the products resultingfrom its interaction with the ehlorin being sodium ehlorid, sodium chlorate. and boric acid, all of which are held in solution by the hot liquid. More or less excess of free chlorin will also be found to be dissolved in the liquor at this stage if the chlorinating action has been carried-as it should bc--to the point of complete decomposition of the borax. The hot liquor brought from the chlorinator is next passed to a refrigerator Q and cooled, any large excess of tree chlorin gas being blown away, such treatment resulting in a copious deposition ot crystallized boric acid, which is then separated from its mother-liquor by the action of a centrifugal R. The boric acid is removed by a conveyer r, and the residual Ynother liquor, which upon standing may deposit a further quantity of boric acid crystals is conveyed to the receptacle S. ATn this spent condition and containing among other substances the sodium chlorate, sodium chlorid and free chlorin previously referred to, it is run into the vat S and may be mixed with the anode liquor from `the electrolytic cells, and then sent on to vthe exhaust gas scrubbers G, there to moet and react with the calcium carbonate residues obtained as a by-product ot the interaction of the berate material and the carbonated liquors as described in a previous portion ot this specification, or the spent. liquor may be separately treated. The 'free ehlorin which such liquors contain, at this point reacts with a portion of the calcium carbonate to vform calcium chlorid and carbon di-oxid'gas which latter goes forward. with the exhaust gas to carbonate the caustic soda liquor as previously described.

The calcium chlorid, sodium chlorate, borate of soda, and free boric acid and salt pass into solution in the spent liquor which may be run to vaste. [f it is desired to recover the. Sodium chlorate, the liquor is not passed through the scrubbers but is concentrated and cooled, boric acid being deposited by crystallization and recovered. The liquor is'ther. further concentrated and the sodium chlorid combined with a small percentage of'boric acidlished out, which forms a very etlicicnt t'ood preservative. After fishing ont the salt at a boiling temperature, the liquor containing a saturated solution of sodium chlor '.te is cooled, and the sodium chlorate crystallized out. l

Claim. A

A process of producingv borax, boric acid and sodium chlorate, which comprises reacting upon a berate of an alkaline earth metal with asolution of a carbonate,'separating a traction ot' the borax from the resulting solution by crystallization, concentrating the mother liquor still containing borax to produce a hot concentrated solution of borax, treating seid hot solution with chlorin gas, andthcreafter separately crystallizing boric acid and sodium chlorate from said liquor.` i

In testimony whereof I atlix my signature in presence ot two witnesses.

ERNEST IAREMNT FLEMIN. lVitnesscs A. J. Darius, B. E. KNIGHT. 

